Genes that follow similar expression trajectories in response to stress or stimulus tend to share biological functions. Thus, it is reasonable and common to cluster genes by expression trajectories.

Epigenetic changes, in particular DNA methylation, accumulate with age across different tissues, but whether these changes follow consistent patterns across different organs remains poorly understood.

The y axis shows the log 10 -normalized expression of the genes. For a – f, boxes indicate the median and interquartile range. g, Dendrogram showing the clustering of the cells in the first experiment ...